Method and apparatus for starting an internal combustion engine

ABSTRACT

A method and apparatus for starting an internal combustion engine is disclosed. A motor is mechanically coupled to the engine, the engine having at least one moveable element mounted in a chamber, the moveable element being operable to cause a changing compression condition within the chamber and being mechanically coupled to a shaft for generating mechanical power. The method involves causing the motor to supply a positioning torque to the engine to move the at least one moveable element into a starting position, The method also involves causing the motor to supply a starting torque to the engine when the at least one moveable element is in the starting position to cause the moveable element to accelerate from the starting position under low compression conditions to generate sufficient momentum to overcome a peak compression condition in the chamber, thereby reducing the starting torque required to start the engine.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates generally to internal combustion engines and moreparticularly to starting an internal combustion engine.

2. Description of Related Art

In general, internal combustion engines are started by applying anexternal starting torque to cause the engine to run up to a speed atwhich sustained combustion of a fuel mixture occurs, thus causing theengine to produce a drive torque. The external starting torque iscommonly provided by an electric starter motor, which is mechanicallycoupled to the engine during starting.

Starter motors are generally configured to turn the engine from astandstill up to a low rotational speed for starting (for example 200rpm). The starter motor must therefore be sized to provide sufficienttorque to turn the engine from a state of rest to overcome peak cylindercompression.

When an engine is stopped it is likely that the engine will come to astandstill when the momentum of the pistons and other moving elements isinsufficient to overcome the cylinder compression. Under theseconditions it is likely that the engine will be at a point in the enginecycle close to a compression stroke, and thus the starter motor mustovercome the peak cylinder compression with little opportunity to buildup momentum. Accordingly a worst case starting torque must be taken intoaccount when selecting a starter motor.

Particularly in hybrid vehicles that employ start/stop operation, anengine may be started many times during a single trip. Furthermore, inhybrid vehicles where the starter motor also functions as a generatorand/or drive motor, the requirement to overcome a worst case startingtorque may result in selection of a motor that does not operateoptimally as a generator and/or drive motor.

SUMMARY OF THE INVENTION

It has been recognized by the inventors that when sizing a motor forstarting an internal combustion engine, accounting for worst caseconditions generally results in over-specifying the torque capacity ofthe motor. Accordingly, in one aspect of the invention there is provideda method for starting an internal combustion engine having a motormechanically coupled to the engine, the engine having at least onemoveable element mounted in a chamber, the moveable element beingoperable to cause a changing compression condition within the chamberand being mechanically coupled to a shaft for generating mechanicalpower. The method involves causing the motor to supply a positioningtorque to the engine to move the at least one moveable element into astarting position. The method also involves causing the motor to supplya starting torque to the engine when the at least one moveable elementis in the starting position to cause the moveable element to acceleratefrom the starting position under low compression conditions to generatesufficient momentum to overcome a peak compression condition in thechamber, thereby reducing the starting torque required to start theengine.

Causing the motor to supply the positioning torque to move the at leastone moveable element into the starting position may involve causing themotor to supply a reference positioning torque to the engine in anopposite direction to the starting torque, the reference positioningtorque having a magnitude sufficient to cause the at least one moveableelement to move to a position at which a force exerted on the moveableelement by the reference torque matches a force exerted on the moveableelement due to the compression condition in the chamber.

Causing the motor to supply the reference positioning torque may involvecalculating the magnitude of the reference positioning torque inresponse to receiving a temperature signal representing an operatingtemperature of the engine.

Causing the motor to supply the positioning torque to move the at leastone moveable element into the starting position may involve causing themotor to supply torque to the engine to cause the moveable element tomove in a direction opposite to a direction required to start theengine, and causing the motor to discontinue supplying torque to theengine when the moveable element reaches the starting position.

Causing the motor to supply torque to the engine may involve causing themoveable element to move at a reference speed.

Causing the motor to discontinue supplying torque to the engine when themoveable element reaches the starting position may involve receiving asignal representing one of a magnitude of the torque supplied by themotor to maintain the reference speed, and a position of the at leastone moveable element in the chamber, and causing the motor todiscontinue supplying torque to the engine when the signal meets acriterion.

Causing the motor to supply torque to the engine may involve causing themotor to supply a reference torque to the engine.

Causing the motor to discontinue supplying torque to the engine when themoveable element reaches the starting position may involve receiving asignal representing one of a position of the at least one moveableelement in the chamber, and a speed of the moveable element, and causingthe motor to discontinue supplying torque to the engine when the signalmeets a criterion.

The at least one moveable element may include a piston received in acylindrical chamber for reciprocating linear motion therein, the pistonbeing mechanically coupled to a crankshaft for converting thereciprocating linear motion into rotary motion of the crankshaft and themethod may further involve mechanically coupling the motor to thecrankshaft to supply the positioning torque and the starting torque tothe piston.

The at least one moveable element may include a plurality of pistons,each being received in a respective cylindrical chamber and coupled to acrankshaft such that, in operation, at least two of the plurality ofpistons have peak compression conditions that occur spaced apart intime, and causing the motor to supply the positioning torque to theengine may involve supplying a torque to the crankshaft to cause theplurality of pistons to move to one of at least two starting positionshaving a low compression condition.

Causing the motor to supply the positioning torque may involve causingthe motor to supply a positioning torque to the engine in response toreceiving an engine control signal having a signal state indicating thatthe engine has been stopped.

The method may involve coupling the mechanical power produced by theengine to at least one drive wheel of a vehicle, and producing theengine control signal in response to receiving a vehicle operatingcondition signal representing at least one operating condition of thevehicle.

Causing the motor to supply the positioning torque may involve producinga motor control signal operable to cause an electrical current to becoupled to the motor to produce the positioning torque.

The method may involve causing the motor to be configured in a generatormode once the engine has been started, the motor being operable toproduce electrical energy in response to receiving a torque from theengine when configured in the generator mode.

At least a portion of the electrical energy produced by the motor in thegenerator mode may be stored in the energy storage element.

The engine may be used in a vehicle, the vehicle may further involve anenergy storage element and a traction motor, the traction motor beingoperably configured to receive electrical energy from an energy storageelement and to convert the electrical energy into a drive torque fordriving the vehicle.

The method may involve coupling the mechanical power produced by theengine to at least one drive wheel of a vehicle.

The method may involve causing the motor to supply a drive torque fordriving the vehicle.

The method may involve decoupling the motor from the engine after theengine has been started.

Causing the motor to supply a positioning torque to the engine mayinvolve mechanically coupling the motor to the engine when the engine isstopped.

In accordance with another aspect of the invention there is provided anapparatus for starting an internal combustion engine. The apparatusincludes a motor mechanically coupled to the engine, the engine havingat least one moveable element mounted in a chamber, the moveable elementbeing operable to cause a changing compression condition within thechamber and being mechanically coupled to a shaft for generatingmechanical power. The apparatus also includes a controller. Thecontroller is operably configured to cause the motor to supply apositioning torque to the engine to move the at least one moveableelement into a starting position. The controller is also operablyconfigured to cause the motor to supply a starting torque to the enginewhen the at least one moveable element is in the starting position tocause the moveable element to accelerate from the starting positionunder low compression conditions to generate sufficient momentum toovercome a peak compression condition in the chamber, thereby reducingthe starting torque required to start the engine.

The controller may be operably configured to cause the motor to supply areference positioning torque to the engine in an opposite direction tothe starting torque, the reference positioning torque having a magnitudesufficient to cause the at least one moveable element to move to aposition at which a force exerted on the moveable element by thereference torque matches a force exerted on the moveable element due tothe compression condition in the chamber.

The controller may be operably configured to calculate the magnitude ofthe reference positioning torque in response to receiving a temperaturesignal representing an operating temperature of the engine.

The controller may be operably configured to cause the motor to supplytorque to the engine to cause the moveable element to move in adirection opposite to a direction required to start the engine, and tocause the motor to discontinue supplying torque to the engine when themoveable element reaches the starting position.

The controller may be operably configured to cause the moveable elementto move at a reference speed.

The controller may be operably configured to receive a signalrepresenting one of a magnitude of the torque supplied by the motor tomaintain the reference speed, and a position of the at least onemoveable element in the chamber, and to cause the motor to discontinuesupplying torque to the engine when the signal meets a criterion.

The controller may be operably configured to cause the motor to supply areference torque to the engine.

The controller may be operably configured to receive a signalrepresenting one of a position of the at least one moveable element inthe chamber, and a speed of the moveable element, and to cause the motorto discontinue supplying torque to the engine when the signal meets acriterion.

The at least one moveable element may include a piston received in acylindrical chamber for reciprocating linear motion therein, the pistonbeing mechanically coupled to a crankshaft for converting thereciprocating linear motion into rotary motion of the crankshaft and themotor may be operably configured to be coupled to the crankshaft tosupply the positioning torque and the starting torque to the piston.

The at least one moveable element may include a plurality of pistons,each being received in a respective cylindrical chamber and coupled to acrankshaft such that, in operation, at least two of the plurality ofpistons have peak compression conditions that occur spaced apart intime, and the controller may be operably configured to cause the motorto supply the positioning torque to the engine by supplying a torque tothe crankshaft to cause the plurality of pistons to move to one of atleast two starting positions having a low compression condition.

The controller may be operably configured to cause the motor to supplythe positioning torque to the engine in response to receiving an enginecontrol signal having a signal state indicating that the engine has beenstopped.

The engine may be used in a vehicle and the controller may be operablyconfigured to produce the engine control signal in response to receivinga vehicle operating condition signal representing at least one operatingcondition of the vehicle.

The engine may be operably configured to couple the mechanical powerproduced by the engine to at least one drive wheel of a vehicle and thecontroller may be operably configured to produce a motor control signaloperable to cause an electrical current to be coupled to the motor toproduce the positioning torque.

The motor may be operable to be configured in a generator mode once theengine has been started, the motor being operable to produce electricalenergy in response to receiving a torque from the engine when configuredin the generator mode.

The energy storage element may be operably configured to store at leasta portion of the electrical energy produced by the motor in thegenerator mode.

The vehicle may further include an energy storage element and a tractionmotor, the traction motor being operably configured to receiveelectrical energy from an energy storage element and to convert theelectrical energy into a drive torque for driving the vehicle.

The engine may be operably configured to couple the mechanical powerproduced by the engine to at least one drive wheel of a vehicle and thecontroller may be operably configured to cause the motor to supply adrive torque for driving the vehicle.

The engine may be operably configured to couple the mechanical powerproduced by the engine to at least one drive wheel of a vehicle.

The motor may be operably configured to decouple from the engine afterthe engine has been started.

The motor may be operably configured supply a positioning torque to theengine by mechanically coupling the motor to the engine when the engineis stopped.

The controller may include a processor circuit.

In accordance with another aspect of the invention there is provided anapparatus for starting an internal combustion engine having a motormechanically coupled to the engine, the engine having at least onemoveable element mounted in a chamber, the moveable element beingoperable to cause a changing compression condition within the chamberand being mechanically coupled to a shaft for generating mechanicalpower. The apparatus includes provisions for causing the motor to supplya positioning torque to the engine to move the at least one moveableelement into a starting position, and provisions for causing the motorto supply a starting torque to the engine when the at least one moveableelement is in the starting position to cause the moveable element toaccelerate from the starting position under low compression conditionsto generate sufficient momentum to overcome a peak compression conditionin the chamber, thereby reducing the starting torque required to startthe engine.

The provisions for causing the motor to supply the positioning torque tomove the at least one moveable element into the starting position mayinclude provisions for causing the motor to supply a referencepositioning torque to the engine in an opposite direction to thestarting torque, the reference positioning torque having a magnitudesufficient to cause the at least one moveable element to move to aposition at which a force exerted on the moveable element by thereference torque matches a force exerted on the moveable element due tothe compression condition in the chamber.

The provisions for causing the motor to supply the reference positioningtorque may include provisions for calculating the magnitude of thereference positioning torque in response to receiving a temperaturesignal representing an operating temperature of the engine.

The provisions for causing the motor to supply the positioning torque tomove the at least one moveable element into the starting position mayinclude provisions for causing the motor to supply torque to the engineto cause the moveable element to move in a direction opposite to adirection required to start the engine, and provisions for causing themotor to discontinue supplying torque to the engine when the moveableelement reaches the starting position.

The provisions for causing the motor to supply torque to the engine mayinclude provisions for causing the moveable element to move at areference speed.

The provisions for causing the motor to discontinue supplying torque tothe engine when the moveable element reaches the starting position mayinclude provisions for receiving a signal representing one of amagnitude of the torque supplied by the motor to maintain the referencespeed, and a position of the at least one moveable element in thechamber, and provisions for causing the motor to discontinue supplyingtorque to the engine when the signal meets a criterion.

The provisions for causing the motor to supply torque to the engine mayinclude provisions for causing the motor to supply a reference torque tothe engine.

The provisions for causing the motor to discontinue supplying torque tothe engine when the moveable element reaches the starting position mayinclude provisions for receiving a signal representing one of a positionof the at least one moveable element in the chamber, and a speed of themoveable element, and provisions for causing the motor to discontinuesupplying torque to the engine when the signal meets a criterion.

The at least one moveable element may include a piston received in acylindrical chamber for reciprocating linear motion therein, the pistonbeing mechanically coupled to a crankshaft for converting thereciprocating linear motion into rotary motion of the crankshaft and theapparatus may include provisions for mechanically coupling the motor tothe crankshaft to supply the positioning torque and the starting torqueto the piston.

The at least one moveable element may include a plurality of pistons,each being received in a respective cylindrical chamber and coupled to acrankshaft such that, in operation, at least two of the plurality ofpistons have peak compression conditions that occur spaced apart intime, and the provisions for causing the motor to supply the positioningtorque to the engine may include provisions for supplying a torque tothe crankshaft to cause the plurality of pistons to move to one of atleast two starting positions having a low compression condition.

The provisions for causing the motor to supply the positioning torquemay include provisions for causing the motor to supply a positioningtorque to the engine in response to receiving an engine control signalhaving a signal state indicating that the engine has been stopped.

The apparatus may include provisions for coupling the mechanical powerproduced by the engine to at least one drive wheel of a vehicle, andprovisions for producing the engine control signal in response toreceiving a vehicle operating condition signal representing at least oneoperating condition of the vehicle.

The provisions for causing the motor to supply the positioning torquemay include provisions for producing a motor control signal operable tocause an electrical current to be coupled to the motor to produce thepositioning torque.

The apparatus may include provisions for causing the motor to beconfigured in a generator mode once the engine has been started, themotor being operable to produce electrical energy in response toreceiving a torque from the engine when configured in the generatormode.

The provisions for storing energy may be operably configured to storethe electrical energy produced by the motor in the generator mode.

The engine may be used in a vehicle, the vehicle may further includeprovisions for storing energy and a traction motor, the traction motorbeing operably configured to receive electrical energy from theprovisions for storing energy and to convert the electrical energy intoa drive torque for driving the vehicle.

The apparatus may include provisions for coupling the mechanical powerproduced by the engine to at least one drive wheel of a vehicle.

The apparatus may include provisions for causing the motor to supply adrive torque for driving the vehicle.

The apparatus may include provisions for decoupling the motor from theengine after the engine has been started.

The provisions for causing the motor to supply a positioning torque tothe engine may include provisions for mechanically coupling the motor tothe engine when the engine may be stopped.

In accordance with another aspect of the invention there is provided acomputer readable medium encoded with codes for directing a processorcircuit to start an internal combustion engine, the internal combustionengine having a motor mechanically coupled to the engine, the enginehaving at least one moveable element mounted in a chamber, the moveableelement being operable to cause a changing compression condition withinthe chamber and being mechanically coupled to a shaft for generatingmechanical power. The codes direct the processor circuit to cause themotor to supply a positioning torque to the engine to move the at leastone moveable element into a starting position. The codes also direct theprocessor circuit to cause the motor to supply a starting torque to theengine when the at least one moveable element is in the startingposition to cause the moveable element to accelerate from the startingposition under low compression conditions to generate sufficientmomentum to overcome a peak compression condition in the chamber,thereby reducing the starting torque required to start the engine.

In accordance with another aspect of the invention there is provided acomputer readable signal encoded with codes for directing a processorcircuit to start an internal combustion engine, the internal combustionengine having a motor mechanically coupled to the engine, the enginehaving at least one moveable element mounted in a chamber, the moveableelement being operable to cause a changing compression condition withinthe chamber and being mechanically coupled to a shaft for generatingmechanical power. The codes direct the processor circuit to cause themotor to supply a positioning torque to the engine to move the at leastone moveable element into a starting position. The codes also direct theprocessor circuit to cause the motor to supply a starting torque to theengine when the at least one moveable element is in the startingposition to cause the moveable element to accelerate from the startingposition under low compression conditions to generate sufficientmomentum to overcome a peak compression condition in the chamber,thereby reducing the starting torque required to start the engine. Otheraspects and features of the present invention will become apparent tothose ordinarily skilled in the art upon review of the followingdescription of specific embodiments of the invention in conjunction withthe accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate embodiments of the invention,

FIG. 1 is a schematic view of a first embodiment of an apparatus forstarting an internal combustion engine;

FIG. 2 is a cutaway perspective view of an engine shown in FIG. 1;

FIG. 3 is an idealized graphical depiction of torque provided by a motorshown in FIG. 1 during starting of the engine shown in FIG. 2;

FIG. 4 is a flowchart of a process for starting the engine shown in FIG.2;

FIG. 5 is a schematic view of a hybrid vehicle embodiment of theinvention;

FIG. 6 is a schematic view of processor circuit for implementing acontroller shown in FIG. 5;

FIG. 7 is a flowchart including blocks of codes for directing theprocessor circuit shown in FIG. 6 to start an engine shown in FIG. 5 inaccordance with an embodiment of the invention; and

FIG. 8 is a flowchart including blocks of codes for directing theprocessor circuit shown in FIG. 6 to move the engine to a startingposition in accordance with one embodiment of the invention;

FIG. 9 is a flowchart including blocks of codes for directing theprocessor circuit shown in FIG. 6 to move the engine to a startingposition in accordance with another embodiment of the invention;

FIG. 10 is a flowchart including blocks of codes for directing theprocessor circuit shown in FIG. 6 to move the engine to a startingposition in accordance with yet another embodiment of the invention; and

FIG. 11 is a flowchart including blocks of codes for directing theprocessor circuit shown in FIG. 6 to move the engine to a startingposition in accordance with yet another embodiment of the invention.

DETAILED DESCRIPTION

Referring to FIG. 1, an apparatus for starting an internal combustionengine in accordance with a first embodiment of the invention is showngenerally at 100. The apparatus 100 includes a motor 102, which ismechanically coupled to an engine 104. The engine 104 has at least onemoveable element 106, which is mounted in a chamber 108. The moveableelement 106 is operable to cause a changing compression condition withinthe chamber 108 and is mechanically coupled to a shaft 110 forgenerating mechanical power.

The apparatus 100 also includes a controller 112, which is operablyconfigured to cause the motor 102 to supply a positioning torque to theengine 104 to move the at least one moveable element 106 into a startingposition. The controller 112 is also operably configured to cause themotor 102 to supply a starting torque to the engine 104 when themoveable element 106 is in the starting position, to cause the moveableelement to accelerate from the starting position under low compressionconditions and to generate sufficient momentum to overcome a peakcompression condition in the chamber 108. Advantageously, by moving theat least one moveable element 106 into a starting position, theapparatus 100 reduces the starting torque required to be supplied by themotor 102 in order to start the engine 104.

In the embodiment shown in FIG. 1, the engine includes a flywheel 124coupled to the engine 104 by a shaft 126. The motor 102 includes a gear120 which meshes with an internal gear surface (shown in broken line at122) of the engine flywheel 124 for mechanically coupling torqueproduced by the motor to the engine 104. In other embodiments the motor102 may be directly coupled to the engine 104, or may be coupled to theengine by a belt, chain, or any other mechanical coupling means. Theshaft 110 may also be coupled to the engine on the same side as theflywheel 124.

In the embodiment shown the motor 102 is an electrical motor and theapparatus 100 further includes an energy storage element 103 forproviding electrical energy to the motor. In other embodiments the motormay be a hydraulic motor or a pneumatic motor, for example.

In this embodiment, the controller 112 includes an output 114 forproducing a motor control signal for controlling the motor 102 and themotor includes an input 118 for receiving the motor control signal. Themotor 102 receives electrical energy from the storage element 103 andconverts the electrical energy into a mechanical torque in response tothe motor control signal. The motor control signal thus controls amagnitude and a direction of the positioning and starting torque. Inthis embodiment, the positioning torque has a lower magnitude and is inan opposite direction to the starting torque.

The storage element 103 may comprise a plurality of cells. In oneembodiment, the cells in the storage element 103 may includeelectrochemical cells, such as nickel metal hydride (NiMH) storagecells. In other embodiments, the storage element 103 may include acombination of electrochemical cells and/or a storage capacitor element,such as an ultra-capacitor (also know as a supercapacitor), for example.

In other embodiments, the motor 102 may be selectively mechanicallycoupled to the engine 104 when the motor control signal is received atthe input 118. For example, the motor 102 may include a conventionalsolenoid (not shown) for connecting the starter motor to a source ofelectrical energy and for activating a drive pinion to engage theinternal gear surface 122 of the flywheel 124.

The controller 112 also optionally includes an input 116 for receivingone or more engine control signals. The engine control signal mayrepresent a state of the engine 104 such as whether the engine isrunning or stopped. Alternatively, the engine control signal mayrepresent a torque provided on the shaft 126 to the engine or a motorposition signal representing a position of the moveable element 106 orthe flywheel 124, or the shaft 110, for example.

In this embodiment, the controller 112 includes an input 128 forreceiving an engine temperature signal. The temperature signal may beproduced by a temperature sensor that is located to sense a temperatureof the chamber 108, a coolant for cooling the engine 104, an engineblock, or a lubricating fluid (i.e. the engine oil), for example.

The engine 104 is shown in greater detail in FIG. 2. Referring to FIG. 2the engine 104 includes four moveable pistons 130, 132, 134, and 136,each being received in respective cylindrical chambers 138, 140, 142,and 144 for reciprocating linear motion therein. The pistons 130-136 areeach mechanically coupled to a crankshaft 146 for converting thereciprocating linear motion into rotary motion of the crankshaft. Inother embodiments different piston configurations and number of pistonsmay be employed such as a V6 or flat configuration, for example.

In this embodiment the flywheel 124 couples motor torque to the engineand further provides an inertial mass for reducing torque pulsations dueto combustion within the cylinders 138-144. The engine 104 also includesvarious other components (not shown in FIG. 2) for conventionallyimplementing a four stroke Otto cycle engine, such as intake valves,exhaust valves, and ignition components.

In other embodiments, the engine may have an alternative moveableelement configuration, such as a rotary piston within an epitrochoidalchamber as is used in a Wankel engine, for example.

In a four cylinder four stroke engine such as the engine 104 shown inFIG. 2, one complete engine cycle occurs over two revolutions (720°) ofthe crankshaft 146 and the pistons thus move in pairs (130, 136 and 132,134). Each pair is thus always at the same position within therespective cylinders, but is 360° out of phase within the cycle. Forexample the piston pair 130 and 136 shown in FIG. 2 are both near thetop of their respective strokes, but only one will be on a firing stroke(i.e. ignition of a fuel mixture) while the other will be on an intakestroke (i.e. intake of the fuel mixture). Similarly for the piston pair132 and 134, one will be in a compression stroke (compressing the fuelmixture) while the other will be on an exhaust stroke (exhaustingcombusted fuel products). When the engine 104 is operating, the torquerequired to perform the compression stroke is provided by the piston onthe firing stroke (for example, for a 1, 3, 4, 2 firing order of thepistons 130-136, when piston 130 is fired, piston 134 is on acompression stroke). However, when starting the engine 104, the torquefor providing compression must be supplied from an external motiveforce, such as from the motor 102 shown in FIG. 1.

Referring to FIG. 3, an idealized graphical depiction of the torqueprovided by the motor 102 to turn the engine 104 against compressionduring starting is shown generally at 160. The torque varies between alow compression condition 162, which occurs when a compression stroke isjust about to commence, and a peak compression condition when acompression stroke is completed and firing is just about to occur. Thegraphical depiction 160 is idealized in that a moment of inertia at restof the pistons 130-136, crankshaft 146, and flywheel 124, has not beentaken into account, and the momentum of these moving elements onceaccelerated from rest, has also not been taken into account. Suchfactors would have the effect of altering the shape and/or magnitude ofsubsequent peaks 164 of the graphical depiction 160. The graphicaldepiction 160 also applies to a portion of the starting cycle beforecombustion of fuel in the chamber 108 provides a further torque inaddition to the torque provided by the motor 102.

Referring to FIG. 4, a process for starting the engine 104 shown in FIG.1 is shown generally at 200. As shown at 202, the process begins when anengine control signal that has a state indicating that the engine 104has stopped is received at the input 116 of the controller 112.

Referring back to FIG. 3, when stopped, the engine 104 will likely cometo a standstill at one of a plurality of stop positions 166-172 wherethe engine momentum due to motion of the pistons 130-136, crankshaft146, and flywheel 124 becomes insufficient to overcome compression inthe cylinders 138-144. In general, the engine 104 would be equallylikely to come to a standstill at one of the stop positions 166-172shown in FIG. 3, depending on when the ignition signal is interruptedand the momentum of the moveable elements in the engine 104.

As shown at 204, the process then continues when the controller 112produces a motor control signal at the output 114 that causes the motor102 to supply a reference positioning torque to the engine 104. Thereference positioning torque may be a fixed pre-determined torque valuefor the engine 104, or alternatively may be a an adaptive thresholdtorque value that changes in response to temperature and/or otherenvironmental or engine conditions. Accordingly the referencepositioning torque may be selected in response to the temperature signalreceived at the input 128 of the controller 112. For example, inembodiments where the controller 112 is implemented using a processorcircuit such as described later herein, the reference positioning torquemay be calculated or selected from a look-up table. The reference torquemay also be varied as a function of engine rotational position, forexample, such that the reference torque value changes as the moveableelement approaches the starting position.

The engine 104 responds to the reference positioning torque by movingaway from the stopped position (for example the stop position 166) in adirection indicated by the arrow 174 in FIG. 3. The stop position 166 ison the compression stroke of the piston 136 and thus the engine 104moves away from the compression stroke of the piston 136 and encounterscompression due to the piston 134 moving against compression of thecylinder 142. When a force exerted by the reference torque matches aforce exerted on the pistons 134 due to the compression condition in thecylinder 142, the engine 104 once again comes to a standstill at astarting position 176.

As shown at 206, the process continues when the controller 112 producesa motor control signal that causes the motor 102 to discontinueproducing the reference positioning torque. When the positioning torqueis removed, the engine 104 may reposition to a new starting position 178due to forces exerted on the piston 134 by the compression condition inthe cylinder 142. In general, the process steps 204 and 206 cause themotor control signal to be active for a time sufficient to move theengine from the stop position 166 to the starting position 176.Accordingly, the motor control signal may be active for some fixed timeduration dependent on the type of engine.

As shown at 208, the process 200 is then suspended waiting for an enginecontrol signal to be received at the input 116. The process 200 resumesat 210 when the engine control signal representing a request or commandto start the engine 104 is received at the input 116. Alternatively, thewait state 208 and resume state 210 may be eliminated by initiating theprocess 200 only when an engine start command is received, at which timeblocks 204, 206, and 212 may be executed in sequence.

As shown at 212, the controller 112 then produces a motor control signalto cause the motor 102 to produce a starting torque for starting theengine 104. In this embodiment the starting torque causes the engine 104to move from the starting position 176 or 178 shown in FIG. 3 toward thestop position 166, through the compression stroke of the piston 136, andthrough successive subsequent compression strokes of pistons 130 to 136until the engine is started.

In alternative embodiments, when the engine 104 stops at the stopposition 166 the reference positioning torque may be applied in adirection opposite to the direction indicated by the arrow 174, whichcauses the piston 144 to move through the compression stroke to astarting position 180. In this alternative embodiment, the direction ofthe reference positioning torque and the direction of the startingtorque are the same.

The engine 104 shown in FIG. 1 and FIG. 2 may be used to provide drivepower for a motor vehicle, locomotive, or ship, for example.Alternatively the engine may be used to drive a generator for generatingelectrical energy.

Hybrid Vehicle Embodiment

Referring to FIG. 5, an exemplary hybrid vehicle embodiment of theinvention is shown generally at 250. The hybrid vehicle 250 includes anengine 252 which is mechanically coupled through a transmission 254 anddifferential 256 to a pair of drive wheels 258 for driving the hybridvehicle.

In this embodiment, a starter motor 260 is coupled to the engine 252through a flywheel 261 as described above in connection with FIG. 1. Themotor 260 is coupled to an energy bus 263 for receiving electricalenergy for producing torque. The energy bus 263 is in turn coupled to anenergy storage element 262, which may supply energy to the energy bus orreceive energy from the energy bus to maintain a charge of the storageelement. The motor 260 also includes a motor interface 264 for receivingcontrol signals for controlling the motor and for producing signalsrepresenting motor operating conditions. For example, the motorinterface 264 may include a current controller (not shown) that controlsa current supplied to the motor from the energy bus 263 in response toreceiving a current control signal.

The hybrid vehicle 250 also includes a controller 266 for controllingoperation of the vehicle. In this embodiment the controller 266 is shownas a single integrated controller, but in some implementationscontroller functions may be distributed between a plurality of differentcontrollers, which may be located in any of the engine 252, the motor260, the energy storage element 262, and/or the transmission 254, forexample.

The controller 266 includes an output 268 for producing motor controlsignals operable to request a torque τ_(r) and/or a speed s_(r) of themotor, and an output 270 for producing an engine stop signal and/or anengine start signal. In this embodiment, the controller 266 includes aninput 272 for receiving motor operating condition signals representing,for example, an actual torque being produced by the motor 260, an actualspeed of the motor, and/or an angular position of the motor. In someembodiments, the motor may include a position sensor such as aHall-effect sensor for generating the motor speed and/or position.Alternatively, since the torque coupled by the motor 260 is coupled tothe engine 252, torque and speed signals may alternatively be producedat the engine and coupled to the input 172 of the controller 266.

The engine 252 includes an engine interface 271 for producing signalsindicative of engine operating conditions, and the controller 266includes inputs for receiving the engine operating condition signalsproduced by the engine interface. The engine interface 271 may comprisean Engine Control Unit (ECU) that controls various aspects of theoperation of the engine 252. In this embodiment, the controller 266includes an input 276 for receiving a position signal. The positionsignal may be produced by any of a variety of sensors which are locatedto sense motion of a moving part of the engine. For example a rotaryshaft encoder may be located to sense movement of the flywheel 261 fromwhich the piston positions can be derived. Alternatively a Hall-effectsensor may be located to sense movement of the crankshaft or the pistonsor signals produced by or for the ignition system may be used to producethe position signals.

The controller 266 further includes an input 278 for receiving vehicleoperating condition signals. In the embodiment shown, the hybrid vehicle250 includes a vehicle velocity sensor 280 for producing a signalrepresenting the velocity of the vehicle and an operator input device282 having an output 284 for producing a demand signal. The operatorinput device 282 may include a foot pedal disposed in a drivingcompartment (not shown) of the hybrid vehicle 250, which is configuredto produce the demand signal in response to an operator depressing thepedal, for example.

Optionally, the hybrid vehicle 250 may also include a traction motor 286operable to produce mechanical power for driving the vehicle. Thetraction motor 286 includes an input 288 for receiving electrical energyfrom the energy bus 263, and is operable to convert the electricalenergy into a torque, which is coupled to the drive wheels 258.

In other embodiments, the hybrid vehicle may include the traction motor286, the engine 252, and the motor 260, as shown in FIG. 5, but withoutthe coupling of the engine through the transmission 254 to the drivewheels 258. In such an embodiment (known as a serial hybrid vehicle) theengine and motor operate as a generator set for supplying electricalenergy to the energy bus 263, and the traction motor 286 supplies therequired drive power to the wheels 258.

Controller

Referring to FIG. 6, in one embodiment the controller 266 may beimplemented using a processor circuit shown generally at 300. Theprocessor circuit 300 includes a microprocessor 302, a program memory304, a variable memory 306, a parameter memory 308, a media reader 310,and an input output port (I/O) 312, all of which are in communicationwith the microprocessor 302.

Program codes for directing the microprocessor 302 to carry out variousfunctions are stored in the program memory 304, which may be implementedas a random access memory (RAM), as a read only memory (ROM) and/or ahard disk drive (HDD), or a combination thereof. The program memoryincludes a first block of program codes 320 for directing themicroprocessor 302 to perform operating system functions and a secondblock of program codes 322 for directing the microprocessor 302 tocontrol starting of the engine 252.

The media reader 310 facilitates loading program codes into the programmemory 304 from a computer readable medium 314, such as a CD ROM disk316, or a computer readable signal 318, such as may be received over anetwork such as a controller area network (CAN), which may beimplemented in the vehicle 250, for example.

The I/O 312 includes the input 272 for receiving the motor operatingcondition signal (torque, speed), the input 276 for receiving theposition signal, and the input 278 for receiving the vehicle operatingcondition signals. The I/O 312 also includes the output 268 forproducing the motor control signals (torque and/or speed), and theoutput 270 for producing the engine stop/start signal.

The variable memory 306 includes a plurality of storage locationsincluding a store 350 for storing operating condition signal values, astore 352 for storing motor torque values, a store 354 for storing motorposition values, and a store 356 for storing motor speed values. Thevariable memory 306 may be implemented in random access memory, forexample.

The parameter memory 308 includes a plurality of storage locations,including a store 360 for storing values representing engine stopcriteria, a store 362 for storing an engine stopped speed s₀, a store364 for storing a motor reference speed value, a store 366 for storing atorque criterion value, a store 368 for storing engine start criteria, astore 370 for storing an engine rotational position criterion, and astore 371 for storing motor speed criteria. The parameter memory 308 maybe implemented in random access memory, for example.

In other embodiments (not shown), the controller 266 shown in FIG. 5 maybe partly or fully implemented using a hardware logic circuit includingdiscrete logic circuits and/or an application specific integratedcircuit (ASIC).

Hybrid Vehicle Operation

Referring to FIG. 7, a flowchart depicting blocks of code for directingthe processor circuit 300 to operate the hybrid vehicle 250 is showngenerally at 400. The process begins at block 402, which directs themicroprocessor 302 to receive the operating condition signals at theinput 278 of the I/O 312 and to store operating condition values in thestore 350 of the variable memory 306.

Block 404 then directs the microprocessor 302 read the criteria forstopping the engine in the store 360 of the parameter memory 308, and tocompare the operating condition signal values in the store 350 againstthe criteria. If the operating condition signal values do not meet thecriteria for stopping the engine, then block 404 directs themicroprocessor 302 back to block 402.

If at block 404 the operating condition signal values meet the criteria,then block 404 directs the microprocessor 302 to block 406. For examplewhen the vehicle velocity sensor 280 produces a signal indicating thatthe hybrid vehicle 250 has stopped, and no operator input is received atthe operator input device 282, then it is likely that the vehicle has atleast temporarily halted (for example at a traffic signal), and theengine should be stopped.

Block 406 directs the microprocessor 302 to cause the I/O 312 to producethe engine stop signal at the output 270. The engine stop signal isreceived by the engine interface 271 and causes the engine to be stoppedby interrupting engine ignition, for example. In general, the momentumof the moving components of the engine will cause the engine to run onfor several engine cycles before coming to a standstill, and accordinglyblock 406 also directs the microprocessor 302 to read the engine stopspeed parameter s₀ from the store 362 of the parameter memory 308, andto wait until the engine speed is less than s₀. In practice, s₀ may be alow engine speed such as 5 rpm, for example. Alternatively, the enginestopped condition may be inferred from an engine crankshaft positionfeedback signal, for example. As described above in connection with FIG.3, the engine is likely to come to a standstill at one of the pluralityof stop positions 166-172.

The process then continues at block 408, which directs themicroprocessor 302 to produce a signal at the output 268 of the I/O tocause the motor 260 to supply torque to the engine 252 in a directionopposite to a direction required for starting the engine 252. The motor260 thus causes the engine to be moved towards the starting position(such as the position 176 shown in FIG. 3).

Block 412 then directs the microprocessor 302 to determine whether theengine is in a starting position. If the engine is not in a startingposition block 412 directs the microprocessor back to block 408. If theengine is in the starting position block 412 directs the microprocessor302 to block 414. Blocks 408 and 412 are described in greater detaillater herein.

Block 414 directs the microprocessor 302 to produce a signal at theoutput 268 that causes the motor to discontinue supplying torque to theengine (i.e. s_(r)=0). As described above, when the motor torque isdiscontinued, the cylinder compression acting on the pistons may causethe engine to move to a position 178, which becomes the new startingposition.

The process 400 then continues at block 416 which directs themicroprocessor 302 to again receive operating condition signals at theinput 278 and to store the operating condition signal values in thestore 350. Block 418 then directs the microprocessor 302 to read theengine start criteria from the store 368 of the parameter memory 308,and to compare the operating condition values in the store 350 againstthe start criteria. If the operating conditions do not meet the enginestart criteria then block 418 directs the microprocessor 302 back toblock 416.

If at block 418 the operating conditions meet the engine start criteriathen the process continues at block 420. For example, in the hybridvehicle 250, the engine start signal may be produced when the operatorinput device 282 receives user input of a demand for torque to besupplied to the drive wheels 258, and the vehicle velocity sensor 280produces a signal indicating that the vehicle velocity has reached avelocity at which the engine should be started. Other vehicle operatingconditions such as environmental or terrain indications may also betaken into account as engine start criteria.

The process then continues at block 420, which directs themicroprocessor 302 to produce an engine start signal at the output 270.The engine 252 receives the start signal at the engine interface 271 andproduces ignition signals for starting the engine. Block 422 thendirects the microprocessor 302 to produce a starting torque signal atthe output 268 of the I/O 312, which causes the motor 260 to produce thestarting torque for starting the engine.

Advantageously, by configuring the engine 252 to the starting positionthe torque required for starting is minimized. Furthermore, in somehybrid vehicle embodiments when the vehicle is moving at the time theengine is started, torque spikes in the drive torque may be prevented orat least reduced.

Referring to FIG. 8, one possible embodiment of the process blocks 408and 412 in the process 400 is shown generally at 440. The blocks in theprocess 440 replace blocks 408 and 412 shown in FIG. 7, while blocks402-406, and 414-422 in FIG. 7 remain unchanged. Accordingly, afterblock 406 directs the microprocessor 302 to produce the engine stopsignal, the process 440 begins at block 442.

Block 442 directs the microprocessor 302 to produce a control signal atthe output 268, which requests the motor to rotate at the referencespeed thus moving the moveable elements (pistons and crankshaft) in theengine 252.

Block 444 then directs the microprocessor 302 to receive the signal atthe input 272 representing the actual torque produced by the motor 260to maintain the reference speed. Block 444 also directs themicroprocessor 302 to store the actual torque value in the store 352 ofthe variable memory 306. The actual torque produced by the motor 260 isgenerally indicative of the compression condition produced by thepistons within the respective cylinders.

Block 446 then directs the microprocessor 302 to read the torquecriterion from the store 366 of the parameter memory 308 and to comparethe actual torque value in the store 352 with the torque criterion. Ifthe actual torque is less then the torque criterion then the torquecriterion is not met and block 446 directs the microprocessor 302 backto block 444. If the actual torque is greater than or equal to thetorque criterion for a first period of time then the torque criterion ismet and block 446 directs the microprocessor 302 to block 414 in FIG. 7.In practice, the first period of time is generally selected to causespurious torque signals that momentarily exceed torque criterion to bedisregarded. For example, the first time period may be about 1 second.

Referring to FIG. 9, another possible embodiment of the process blocks408 and 412 in the process 400 is shown generally at 450. The blocks inthe process 450 replace blocks 408 and 412 shown in FIG. 7, while blocks402-406, and 414-422 in FIG. 7 remain unchanged. Accordingly, afterblock 406 directs the microprocessor 302 to produce the engine stopsignal, the process 450 begins at block 452.

Block 452 directs the microprocessor 302 to produce a motor controlsignal at the output 268, which requests the motor to rotate at areference speed.

Block 454 then directs the microprocessor 302 to receive the positionsignal at the input 276 of the I/O 312 and to store the position signalvalue in the store 354 of the variable memory 306. Alternatively, inother embodiments, the position signal could be a motor position signalreceived at the input 272 of the I/O, and from which the enginerotational position can be inferred.

Block 456 then directs the microprocessor 302 to read the enginerotational position criterion from the store 370 of the parameter memory308 and to compare the actual engine rotational position against thecriterion. If the position does not meet the position criterion thenblock 456 directs the microprocessor 302 back to block 454. If at block456, the engine rotational position meets the position criterion thenblock 456 directs the microprocessor 302 to block 414 in FIG. 7.

Referring to FIG. 10, another possible embodiment of the process blocks408 and 412 in the process 400 is shown generally at 460. The blocks inthe process 460 replace blocks 408 and 412 shown in FIG. 7, while blocks402-406, and 414-422 in FIG. 7 remain unchanged. Accordingly, afterblock 406 directs the microprocessor 302 to produce the engine stopsignal, the process 460 begins at block 462.

Block 462 directs the microprocessor 302 to produce a control signal atthe output 268, which requests the motor to supply a reference torque tothe engine.

Block 464 then directs the microprocessor 302 to receive the actualmotor speed signal at the input 272 of the I/O 312 and to store thespeed signal value in the store 356 of the variable memory 306.Alternatively, in other embodiments, the speed signal could be receivedfrom an engine speed sensor (not shown).

Block 466 then directs the microprocessor 302 to read the motor speedcriterion from the store 371 of the parameter memory 308 and to comparethe actual motor speed against the criterion. If the motor speed doesnot meet the speed criterion, then block 466 directs the microprocessor302 back to block 474. If at block 466, the motor speed meets the speedcriterion then block 476 directs the microprocessor 302 to block 414 inFIG. 7. For example, the motor speed criterion may require that thespeed reduce below a minimum, which indicates that the reference torqueis being countered by the compression of the cylinder.

Referring to FIG. 11, another possible embodiment of the process blocks408 and 412 in the process 400 is shown generally at 470. The blocks inthe process 450 replace blocks 408 and 412 shown in FIG. 7, while blocks402-406, and 414-422 in FIG. 7 remain unchanged. Accordingly, afterblock 406 directs the microprocessor 302 to produce the engine stopsignal, the process 470 begins at block 472.

Block 472 directs the microprocessor 302 to produce a control signal atthe output 268, which requests the motor to supply a reference torque tothe engine.

Block 474 then directs the microprocessor 302 to receive the positionsignal at the input 276 of the I/O 312 and to store the position signalvalue in the store 354 of the variable memory 306. Alternatively, inother embodiments, the position signal could be a motor position signalreceived at the input 272 of the I/O, and from which the enginerotational position can be inferred.

Block 476 then directs the microprocessor 302 to read the enginerotational position criterion from the store 370 of the parameter memory308 and to compare the actual engine rotational position against thecriterion. If the position does not meet the criterion then block 476directs the microprocessor 302 back to block 474. If at block 456, theengine rotational position meets the criterion then block 476 directsthe microprocessor 302 to block 414 in FIG. 7.

Integrated starter generator embodiment

Referring back to FIG. 5, in embodiments in which the optional tractionmotor 286 is not included, the motor 260 may perform functions ofstarting the engine and generating electrical energy for charging thestorage element 262. When generating electrical energy, the motor 260receives mechanical power from the engine 252 and produces electricalenergy, which is coupled onto the energy bus 263. The energy coupledonto the energy bus 263 may be used for driving the hybrid vehicle 250,charging the storage element 262, and/or powering vehicle accessories(not shown). In this embodiment the ISG may be permanently coupled tothe engine, and selectively configured between a starter motor mode anda generator mode. Alternatively, the ISG may be selectively decoupledfrom the engine when there is no requirement for charging of the storageelement, thus reducing parasitic loads on the engine.

In other embodiments that omit the traction motor 286, the motor 260 mayalso be configured to provide drive power to the wheels 258 by couplingtorque through the engine crankshaft to the transmission 254. The drivepower supplied by the motor 260 may be additive to power produced by theengine or may applied when the engine is not started.

Advantageously, the methods and apparatus described above facilitate areduction of the peak starting torque required for starting an engine.Reduction of peak starting torque allows a smaller and less costlystarter motor to be used. Alternatively, the reduction of startingtorque may facilitate selection of a motor that is better suited forother functions that the motor is required to provide, such asgenerating drive power of the vehicle and/or generating electricalenergy.

While specific embodiments of the invention have been described andillustrated, such embodiments should be considered illustrative of theinvention only and not as limiting the invention as construed inaccordance with the accompanying claims.

What is claimed is:
 1. A method for starting an internal combustion engine having a motor mechanically coupled to the engine, the engine having at least one moveable element mounted in a chamber, the moveable element being operable to cause a changing compression condition within the chamber as the moveable element moves from a low compression condition through a compression stroke to a peak compression condition, the engine being mechanically coupled to a shaft for generating mechanical power, the method comprising: calculating a reference positioning torque; causing the motor to supply the reference positioning torque to the engine to move the at least one moveable element in a direction opposite to a direction of the compression stroke into a starting position where the positioning torque is opposed by a compression condition due to a firing stroke of the engine; and causing the motor to supply a starting torque to the engine.
 2. The method of claim 1 wherein causing the motor to supply said reference positioning torque to move the at least one moveable element into said starting position comprises causing the motor to supply the reference positioning torque to the engine in an opposite direction to said starting torque, said reference positioning torque having a magnitude sufficient to cause the at least one moveable element to move to a position at which a force exerted on the moveable element by said reference torque matches a force exerted on the moveable element due to the compression condition in the chamber.
 3. The method of claim 2 wherein causing the motor to supply said reference positioning torque comprises calculating said magnitude of said reference positioning torque in response to receiving a temperature signal representing an operating temperature of the engine.
 4. The method of claim 1 wherein causing the motor to supply said reference positioning torque to move the at least one moveable element into said starting position comprises: causing the motor to supply torque to the engine to cause the moveable element to move in a direction opposite to a direction required to start the engine; and causing the motor to discontinue supplying torque to the engine when said moveable element reaches said starting position.
 5. The method of claim 4 wherein causing the motor to supply said reference positioning torque to the engine comprises causing the moveable element to move at a reference speed toward said starting position.
 6. The method of claim 5 wherein causing the motor to discontinue supplying torque to the engine when said moveable element reaches said starting position comprises: receiving a signal representing one of: a magnitude of said torque supplied by the motor to maintain said reference speed; or a position of the at least one moveable element in the chamber; and causing the motor to discontinue supplying torque to the engine when said signal meets a criterion.
 7. The method of claim 4 wherein causing the motor to supply said reference positioning torque to the engine comprises causing the motor to supply the reference positioning torque to the engine to cause the moveable element to move toward said starting position.
 8. The method of claim 7 wherein causing the motor to discontinue supplying torque to the engine when said moveable element reaches said starting position comprises: receiving a signal representing one of: a position of the at least one moveable element in the chamber; or a speed of said moveable element; and causing the motor to discontinue supplying torque to the engine when said signal meets a criterion.
 9. The method of claim 1 wherein the at least one moveable element comprises a piston received in a cylindrical chamber for reciprocating linear motion therein, the piston being mechanically coupled to a crankshaft for converting the reciprocating linear motion into rotary motion of the crankshaft and further comprising mechanically coupling the motor to the crankshaft to supply said reference positioning torque and said starting torque to said piston.
 10. The method of claim 1 wherein said at least one moveable element comprises a plurality of pistons, each being received in a respective cylindrical chamber and coupled to a crankshaft such that, in operation, at least two of the plurality of pistons have peak compression conditions that occur spaced apart in time, and wherein causing the motor to supply said reference positioning torque to the engine comprises supplying a torque to the crankshaft to cause the plurality of pistons to move to one of at least two starting positions having a low compression condition.
 11. The method of claim 1 wherein causing the motor to supply said reference positioning torque comprises causing the motor to supply the reference positioning torque to the engine in response to receiving an engine control signal having a signal state indicating that the engine has been stopped.
 12. The method of claim 1 wherein causing the motor to supply said reference positioning torque comprises producing a motor control signal operable to cause an electrical current to be coupled to the motor to produce said reference positioning torque.
 13. The method of claim 1 further comprising causing the motor to be configured in a generator mode once the engine has been started, the motor being operable to produce electrical energy in response to receiving a torque from the engine when configured in said generator mode.
 14. The method of claim 1 further comprising decoupling the motor from the engine after the engine has been started.
 15. The method of claim 14 wherein causing the motor to supply the reference positioning torque to the engine comprises mechanically coupling the motor to the engine when the engine is stopped.
 16. The method of claim 1 wherein the engine comprises more than one moveable element and wherein causing the motor to supply said reference positioning torque comprises causing the motor to supply the reference positioning torque to the engine to move the at least one moveable element in a direction away from the compression stroke into a starting position where the positioning torque is opposed by a compression condition due to a firing stroke of another moveable element of the engine.
 17. An apparatus for starting an internal combustion engine, the apparatus comprising: an electric motor mechanically coupled to the engine, the engine having at least one moveable element mounted in a chamber, the moveable element being operable to move to cause a changing compression condition within the chamber as the moveable element moves from a low compression condition through a compression stroke to a peak compression condition, the engine being mechanically coupled to a shaft for generating mechanical power; a controller, operably configured to: calculate a reference positioning torque; cause the motor to supply the reference positioning torque to the engine to move the at least one moveable element in a direction opposite to a direction of the compression stroke into a starting position where the positioning torque is opposed by a compression condition due to a firing stroke of the engine; and cause the motor to supply a starting torque to the engine when4he engine.
 18. The apparatus of claim 17 wherein said controller is operably configured to cause the motor to supply the reference positioning torque to the engine in an opposite direction to said starting torque, said reference positioning torque having a magnitude sufficient to cause the at least one moveable element to move to a position at which a force exerted on the moveable element by said reference torque matches a force exerted on the moveable element due to the compression condition in the chamber.
 19. The apparatus of claim 18 wherein said controller is operably configured to calculate said magnitude of said reference positioning torque in response to receiving a temperature signal representing an operating temperature of the engine.
 20. The apparatus of claim 17 wherein said controller is operably configured to: cause the motor to supply torque to the engine to cause the moveable element to move in a direction opposite to a direction required to start the engine; and cause the motor to discontinue supplying torque to the engine when said moveable element reaches said starting position.
 21. The apparatus of claim 17 wherein said controller is operably configured to cause the motor to supply said reference positioning torque by causing the moveable element to move at a reference speed toward said starting position.
 22. The apparatus of claim 21 wherein said controller is operably configured to: receive a signal representing one of: a magnitude of said torque supplied by the motor to maintain said reference speed; or a position of the at least one moveable element in the chamber; and cause the motor to discontinue supplying torque to the engine when said signal meets a criterion.
 23. The apparatus of claim 17 wherein said controller is operably configured to cause the motor to supply said reference positioning torque by causing the motor to supply a reference torque to the engine to cause the moveable element to move toward said starting position.
 24. The apparatus of claim 23 wherein said controller is operably configured to: receive a signal representing one of: a position of the at least one moveable element in the chamber; or a speed of said moveable element; and cause the motor to discontinue supplying torque to the engine when said signal meets a criterion.
 25. The apparatus of claim 17 wherein the at least one moveable element comprises a piston received in a cylindrical chamber for reciprocating linear motion therein, the piston being mechanically coupled to a crankshaft for converting the reciprocating linear motion into rotary motion of the crankshaft and wherein the motor is operably configured to be coupled to the crankshaft to supply said reference positioning torque and said starting torque to said piston.
 26. The apparatus of claim 17 wherein said at least one moveable element comprises a plurality of pistons, each being received in a respective cylindrical chamber and coupled to a crankshaft such that, in operation, at least two of the plurality of pistons have peak compression conditions that occur spaced apart in time, and wherein said controller is operably configured to cause the motor to supply said reference positioning torque to the engine by supplying a torque to the crankshaft to cause the plurality of pistons to move to one of at least two starting positions having a low compression condition.
 27. The apparatus of claim 17 wherein said controller is operably configured to cause the motor to supply said reference positioning torque to the engine in response to receiving an engine control signal having a signal state indicating that the engine has been stopped.
 28. The apparatus of claim 17 wherein the engine is operably configured to couple the mechanical power produced by the engine to at least one drive wheel of a vehicle and wherein said controller is operably configured to produce a motor control signal operable to cause an electrical current to be coupled to the motor to produce said reference positioning torque.
 29. The apparatus of claim 17 wherein the motor is operable to be configured in a generator mode once the engine has been started, the motor being operable to produce electrical energy in response to receiving a torque from the engine when configured in said generator mode.
 30. The apparatus of claim 17 wherein the motor is operably configured to decouple from the engine after the engine has been started.
 31. The apparatus of claim 30 wherein the motor is operably configured supply the reference positioning torque to the engine by mechanically coupling the motor to the engine when the engine is stopped.
 32. The apparatus of claim 17 wherein the engine comprises more than one moveable element and wherein the controller is operably configured to cause the motor to supply said reference positioning torque by causing the motor to supply a positioning torque to the engine to move the at least one moveable element in a direction away from the compression stroke into a starting position where the positioning torque is opposed by a compression condition due to a firing stroke of another moveable element of the engine.
 33. An apparatus for starting an internal combustion engine having an electric motor mechanically coupled to the engine, the engine having at least one moveable element mounted in a chamber, the moveable element being operable to cause a changing compression condition within the chamber as the moveable element moves from a low compression condition through a compression stroke to a peak compression condition, the engine being mechanically coupled to a shaft for generating mechanical power, the apparatus comprising: means for calculating a reference positioning torque; means for causing the motor to supply the reference positioning torque to the engine to move the at least one moveable element in a direction opposite to a direction of the compression stroke into a starting position where the positioning torque is opposed by a compression condition due to a firing stroke of the engine; and means for causing the motor to supply a starting torque to the engine.
 34. The apparatus of claim 33 wherein the engine comprises more than one moveable element and wherein said means for causing the motor to supply said reference positioning torque comprises means for causing the motor to supply a positioning torque to the engine to move the at least one moveable element in a direction away from the compression stroke into a starting position where the positioning torque is opposed by a compression condition due to a firing stroke of another moveable element of the engine.
 35. A computer readable medium encoded with codes for directing a processor circuit to start an internal combustion engine, the internal combustion engine having an electric motor mechanically coupled to the engine, the engine having at least one moveable element mounted in a chamber, the moveable element being operable to cause a changing compression condition within the chamber as the moveable element moves from a low compression condition through a compression stroke to a peak compression condition, the engine being mechanically coupled to a shaft for generating mechanical power, the codes directing the processor circuit to: calculate a reference positioning torque; cause the motor to supply the reference positioning torque to the engine to move the at least one moveable element in a direction opposite to a direction of the compression stroke into a starting position where the positioning torque is opposed by a compression condition due to a firing stroke of the engine; and cause the motor to supply a starting torque to the engine. 